For everyone looking for FIDO2 support, there is a work around that may help you:
Until LastPass support this natively, you can now use FIDO2 keys in Duo (supported in both Firefox and Chrome). Your Duo account can then be used as the MFA option in Duo (make sure to set Use Duo Web SDK when possible to yes in the Duo MFA options in LastPass).
And hey, presto, FIDO2 MFA is enabled for LastPass